Abstract This paper examines the use of natural jute fabric reinforced polymer (JFRP) composite sheets as external strengthening material of reinforced concrete (RC) beams. Pre-damaged RC beam specimens are prepared to represent seismic damage. The shear behaviour of pre-damaged deep RC beams strengthened with JFRP sheets are investigated subjected to non-reversed cyclic three-point bending load test. The JFRP strengthening ratio and the pre-damaged level of RC beam are considered in this study. The test results revealed that JFRP can significantly improve the shear strength capacity of beams. All strengthened beams show a similar failure mode which is a rupture on JFRP sheets. The shear enhancement of JFRP strengthened pre-damaged beams are comparable to that of non-damaged beams strengthened with conventional FRPs, proving the applicability of JFRP strengthening in pre-damaged shear-deficient beams. In addition, the experimental results are compared with the predicted values by the Japanese design codes.

中文翻译：

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天然纤维增强聚合物复合材料加固预损伤钢筋混凝土梁的性能

摘要 本文研究了使用天然黄麻织物增强聚合物 (JFRP) 复合板作为钢筋混凝土 (RC) 梁的外部增强材料。准备好预损坏的 RC 梁试样以表示地震损坏。用 JFRP 板加固预损伤深钢筋混凝土梁的剪切行为进行了非反向循环三点弯曲载荷试验研究。本研究考虑了 JFRP 加固率和 RC 梁的预损伤水平。试验结果表明，JFRP可以显着提高梁的抗剪强度能力。所有加强梁都表现出类似的失效模式，即 JFRP 板的断裂。JFRP 加固的预损伤梁的抗剪增强与常规 FRP 加固的未损坏梁的抗剪增强相当，证明了 JFRP 加固在预损坏抗剪梁中的适用性。此外，实验结果与日本设计规范的预测值进行了比较。